This invention relates generally to a housing for physically and thermally isolating the evaporator section of an air conditioning unit that is mounted on the roof of a vehicle such as a trailer, van or motorized home to provide conditioned air to the cabin of the vehicle.
Such roof top units are generally mounted upon a base pan with the evaporator section located to the front of the pan and the condenser section located to the rear of the pan. The compressor, fan drives and controls are centrally mounted between the front and rear sections on the unit. It was customary in many of the earlier units to create an internal superstructure of sheet metal to which the various unit components were attached or supported and enclosing the entire assembly by means of an outer housing or shroud. This type of assembly was relatively heavy and provided limited access to the component parts of the unit.
As disclosed in U.S. Pat. No. 4,672,818, to Roth many of the sheet metal parts in vehicle roof top units have been replaced by molded plastic sections which reduces the weight that the roof must support and provides freer access to internal parts allowing for improved ease of maintenance. The molded parts exhibited long life and are relatively impervious to weather. The unit described by Roth contains three main molded components that include a roof pan, an intermediate raised deck that runs the length of the roof pan, and an outer housing or shroud that covers the deck and is secured to the pan thereby enclosing the unit. Although the Roth unit represents a decided improvement over the earlier units, the intermediate deck prevents ready access to the components mounted under the deck and makes placement of the heat exchangers in the assembly rather difficult. Although the Roth unit is compartmentalized, the compartments do not truly isolate one section of the unit from another and air is able to move between compartments thus reducing the efficiency of the unit.